US10083789B2 - Apparatus for reducing a magnetic unidirectional flux component in the core of a transformer - Google Patents

Apparatus for reducing a magnetic unidirectional flux component in the core of a transformer Download PDF

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US10083789B2
US10083789B2 US14/890,383 US201314890383A US10083789B2 US 10083789 B2 US10083789 B2 US 10083789B2 US 201314890383 A US201314890383 A US 201314890383A US 10083789 B2 US10083789 B2 US 10083789B2
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transformer
compensation
current source
windings
compensation windings
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US20160125999A1 (en
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Peter Hamberger
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Siemens Energy Global GmbH and Co KG
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Siemens AG
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/38—Auxiliary core members; Auxiliary coils or windings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/42—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils

Definitions

  • the invention relates to an apparatus for reducing a magnetic unidirectional flux component in the core of a transformer, i.e., a three-phase transformer, comprising a plurality of compensation windings that are magnetically coupled to the core of the transformer when used in transformers in the low voltage or medium voltage range and transformers of very high power (power transformers, high voltage direct current transmission transformers).
  • DC-component may, for example, originate from conventional electronic structural components presently in use when controlling electrical drives or even in reactive power compensation.
  • a further cause may be geomagnetically induced currents (GIC).
  • Geomagnetically induced currents occur approximately in ten-year cycles. They are evenly distributed on all (three) phases, may reach up to 30 A per phase and may be discharged via the neutral point of a transformer. This leads to considerable saturation of the core of the transformer in a half-cycle and therefore to a high excitation current in a half-cycle. This additional excitation has a large harmonic component and as a result, via the stray field with the harmonic component, eddy current losses are produced in the windings and core components of the transformer.
  • the transformer behaves in a half-wave in the manner of a reactor.
  • transformers 100 A direct current for the neutral point of the transformer.
  • a further solution for geomagnetically induced currents is represented by a “DC blocker” in which, in principle, a capacitor is connected to the neutral point of the transformer.
  • This solution is problematic as a displacement voltage is produced by charging the capacitor.
  • the displacement voltage on the capacitor is limited so that it is generally not possible to block the entire direct current.
  • a drawback with this solution is also when it results in a short circuit in the transmission network and therefore to zero currents.
  • a controllable current source is provided for feeding current into the compensation windings, where the controllable current source is arranged electrically in series with the compensation windings and specifically with the neutral point thereof, which is formed by the inputs of the compensation windings, a neutral earthing transformer is provided and is electrically conductively connected to the outputs of the compensation windings, and the current source electrically interconnects the neutral point of the compensation windings and the neutral point of the neutral earthing transformer.
  • the principle of the solution in accordance with the invention is once again based on direct current compensation via compensation windings, by current being fed specifically into the compensation windings, the effect thereof counteracting the unidirectional flux component and preventing the magnetizing of the core of the transformer.
  • “counter ampere” turns are introduced into the transformer, where ampere turn is another term for the magnetic flux.
  • the compensation current is introduced into the compensation windings by a controllable current source, where generally one compensation winding is provided for each phase of the transformer.
  • the neutral earthing transformer has the advantage in that direct currents introduced via its neutral point and then uniformly distributed over all (three) of its arms, do not magnetize the core of the neutral earthing transformer.
  • At least one current limiting reactor is electrically arranged in series with the current source. By connecting a current limiting reactor upstream, transient voltages may be effectively filtered out, so that they do not pass through the current source.
  • the controllable current source With the controllable current source, only the current that is required for the compensation of the undesired direct currents is supplied to the compensation windings.
  • the controllable current source is connected to a measuring device for detecting the magnetic unidirectional flux component in the transformer.
  • a measuring device for detecting the magnetic unidirectional flux component in the transformer.
  • Such measuring devices are disclosed, for example, in WO 2012/041368 A1 in the form of a magnetic shunt component with a sensor coil.
  • the shunt component may be arranged on the core of the transformer, such as, adjacent to an arm or the yoke, in order to conduct a portion of the magnetic flux in a bypass. From this magnetic flux conducted in the shunt, a sensor signal that has long-term stability may be very easily obtained via a sensor coil, where the signal after optional signal processing very clearly represents the unidirectional flux component (CD component).
  • the neutral earthing transformer may comprise windings in a zigzag arrangement for improved load distribution.
  • FIG. 1 shows a circuit in accordance with the prior art for introducing compensation current into a compensation winding comprising a thyristor circuit
  • FIG. 2 shows a circuit in accordance with the invention for introducing compensation current into compensation windings via a controllable current source
  • FIG. 3 shows a circuit in accordance with an embodiment of the invention for introducing compensation current into compensation winding via a controllable current source.
  • direct current is introduced in a targeted manner into a compensation winding K to eliminate the direct current magnetizing of the transformer core.
  • a compensation winding K For introducing the required magnetic flux (i.e., direct current ampere turns) into the compensation winding K, use is made of the alternating voltage induced in the compensation winding K, and the compensation winding K functions as an alternating voltage source.
  • a switching unit T configured as a thyristor is connected in series with a current limiting reactor L.
  • the required direct current may be adjusted by voltage-synchronous ignition at a specific ignition time of the thyristor T.
  • the maximum direct current is set which, however, is superimposed by an alternating current having the amplitude of the direct current and the network frequency. If the thyristor T is ignited later, the direct current is smaller but harmonic alternating currents are also produced.
  • the current path in the thyristor T is limited by a current limiting reactor L, and the permitted thermal load of the thyristor T is dimensioned for the current limit.
  • a controllable current source S and a neutral earthing transformer H are used instead of the thyristor T, and in this disclosed embodiment in accordance with the invention also instead of the current limiting reactor L.
  • the controllable current source S is electrically directly connected in series with the compensation windings K 1 , K 2 , K 3 and namely the inputs of the compensation windings K 1 , K 2 , K 3 are connected together at a neutral point P 1 that is directly connected to the current source S.
  • One respective compensation winding K 1 , K 2 , K 3 is arranged on an arm of a three-phase transformer (not shown).
  • the three (the upper in this case) primary windings are each connected at their one terminal end to an output of a compensation winding K 1 , K 2 , K 3 .
  • the other terminal ends are each connected at a terminal end of the three (the lower in this case) secondary windings in a zigzag arrangement.
  • the other terminal ends of the secondary winding are brought together in an artificial neutral point P 2 which is directly connected to the controllable current source S.
  • a zigzag arrangement means that the primary and secondary windings of a phase (in this case a compensation winding) are arranged on different arms of the neutral earthing transformer H and/or that the windings on the same arm belong to different phases (different compensation windings).
  • Primary and secondary windings of the neutral earthing transformer H are of the same size and, therefore, have approximately the same winding number but the current passes through them in different directions. Thus, with the same current in different windings, no flux is induced in the core of the neutral earthing transformer H.
  • the current source S is electrically connected, on the one hand, directly to the neutral point P 1 of the compensation windings K 1 , K 2 , K 3 and, on the other hand, to the neutral point P 2 of the neutral earthing transformer H.
  • a current limiting reactor L could also be arranged electrically in series with the current source S.
  • the controllable current source is at earth potential. It is possible to reach 10 kV, 20 kV or 30 kV at the medium voltage level. At the same time, compensation direct current is reduced, and it is possible to use commercially available current sources.
  • the neutral earthing transformer is very insensitive to direct currents at the neutral point as these are uniformly distributed and do not cause any additional magnetizing of the core.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Ac-Ac Conversion (AREA)
  • Supply And Distribution Of Alternating Current (AREA)
  • Inverter Devices (AREA)
  • Soft Magnetic Materials (AREA)
US14/890,383 2013-05-28 2013-05-28 Apparatus for reducing a magnetic unidirectional flux component in the core of a transformer Active US10083789B2 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2013/060948 WO2014191023A1 (de) 2013-05-28 2013-05-28 Vorrichtung zur verringerung eines magnetischen gleichfluss-anteils im kern eines transformators

Publications (2)

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US20160125999A1 US20160125999A1 (en) 2016-05-05
US10083789B2 true US10083789B2 (en) 2018-09-25

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US14/890,383 Active US10083789B2 (en) 2013-05-28 2013-05-28 Apparatus for reducing a magnetic unidirectional flux component in the core of a transformer

Country Status (7)

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US (1) US10083789B2 (pt)
EP (1) EP3005383B1 (pt)
KR (1) KR101806293B1 (pt)
CN (1) CN105229759B (pt)
BR (1) BR112015029477B8 (pt)
CA (1) CA2910674C (pt)
WO (1) WO2014191023A1 (pt)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
PL3179492T3 (pl) * 2015-12-09 2019-03-29 Siemens Aktiengesellschaft Urządzenie zabezpieczające dla transformatora przed prądami indukowanymi geomagnetycznie
CN115389807B (zh) * 2022-10-27 2023-03-24 国网江西省电力有限公司电力科学研究院 一种基于磁通门的变压器中性点直流电流传感器

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2050082A (en) * 1935-12-12 1936-08-04 Gen Electric Suppression of ground faults on alternating current systems
US4058761A (en) * 1975-05-13 1977-11-15 Associated Electrical Industries Limited Saturated reactors
JPS5913313A (ja) 1982-07-13 1984-01-24 Mitsubishi Electric Corp 変圧器の直流偏磁矯正方法
EP0309255A1 (en) 1987-09-22 1989-03-29 Mitsubishi Denki Kabushiki Kaisha Apparatus and process for detecting direct current magnetic flux deflections of an electrical transformer
JPH09289125A (ja) 1996-04-24 1997-11-04 Toshiba Corp 内鉄形単巻単相変圧器
KR20060050624A (ko) 2004-08-25 2006-05-19 이성호 삼상 다선식 전력라인의 고조파 저감장치
US20070217103A1 (en) * 2004-05-10 2007-09-20 Forskarpatent I Syd Ab Method and equipment for the protection of power systems against geomagnetically induced currents
US20070290670A1 (en) * 2004-08-25 2007-12-20 Lee Sung H Device for Reducing Harmonics in Three-Phase Poly-Wire Power Lines
CN101681716A (zh) 2007-06-12 2010-03-24 西门子变压器奥地利有限责任两合公司 具有单向通量补偿的电力变压器
CN202008919U (zh) * 2011-03-18 2011-10-12 杭州得诚电力科技有限公司 用于低压配电网的曲折变压器
CN102364637A (zh) 2011-10-25 2012-02-29 中国西电电气股份有限公司 一种单相四柱铁心结构的电力变压器的补偿绕组体系
WO2012041367A1 (de) 2010-09-29 2012-04-05 Siemens Transformers Austria Gmbh & Co Kg Anordnung und verfahren zur kompensation eines magnetischen gleichflusses in einem transformatorkern
WO2012041368A1 (de) 2010-09-29 2012-04-05 Siemens Transformers Austria Gmbh & Co Kg Vorrichtung und verfahren zum verringern eines magnetischen gleichfluss-anteils im kern eines transformators

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2050082A (en) * 1935-12-12 1936-08-04 Gen Electric Suppression of ground faults on alternating current systems
US4058761A (en) * 1975-05-13 1977-11-15 Associated Electrical Industries Limited Saturated reactors
JPS5913313A (ja) 1982-07-13 1984-01-24 Mitsubishi Electric Corp 変圧器の直流偏磁矯正方法
EP0309255A1 (en) 1987-09-22 1989-03-29 Mitsubishi Denki Kabushiki Kaisha Apparatus and process for detecting direct current magnetic flux deflections of an electrical transformer
JPH09289125A (ja) 1996-04-24 1997-11-04 Toshiba Corp 内鉄形単巻単相変圧器
US20070217103A1 (en) * 2004-05-10 2007-09-20 Forskarpatent I Syd Ab Method and equipment for the protection of power systems against geomagnetically induced currents
KR20060050624A (ko) 2004-08-25 2006-05-19 이성호 삼상 다선식 전력라인의 고조파 저감장치
US20070290670A1 (en) * 2004-08-25 2007-12-20 Lee Sung H Device for Reducing Harmonics in Three-Phase Poly-Wire Power Lines
CN101681716A (zh) 2007-06-12 2010-03-24 西门子变压器奥地利有限责任两合公司 具有单向通量补偿的电力变压器
US20100194373A1 (en) * 2007-06-12 2010-08-05 Siemens Transformers Austria Gmbh & Co Kg Electrical Transformer with Unidirectional Flux Compensation
WO2012041367A1 (de) 2010-09-29 2012-04-05 Siemens Transformers Austria Gmbh & Co Kg Anordnung und verfahren zur kompensation eines magnetischen gleichflusses in einem transformatorkern
WO2012041368A1 (de) 2010-09-29 2012-04-05 Siemens Transformers Austria Gmbh & Co Kg Vorrichtung und verfahren zum verringern eines magnetischen gleichfluss-anteils im kern eines transformators
CN202008919U (zh) * 2011-03-18 2011-10-12 杭州得诚电力科技有限公司 用于低压配电网的曲折变压器
CN102364637A (zh) 2011-10-25 2012-02-29 中国西电电气股份有限公司 一种单相四柱铁心结构的电力变压器的补偿绕组体系

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
"Zigzag Grounding Transformers", Post Glover, pp. 1-2, 2010.
Notice of Allowance dated Sep. 1, 2017 which issued in the corresponding Korean Patent Application No. 10-2015-7036639.
Office Action dated Aug. 29, 2016 which issued in the corresponding Chinese Patent Application No. 201380076964.8.

Also Published As

Publication number Publication date
CA2910674C (en) 2018-03-13
BR112015029477B8 (pt) 2023-04-25
EP3005383A1 (de) 2016-04-13
KR101806293B1 (ko) 2017-12-07
BR112015029477A2 (pt) 2017-07-25
US20160125999A1 (en) 2016-05-05
WO2014191023A1 (de) 2014-12-04
BR112015029477B1 (pt) 2021-06-29
CA2910674A1 (en) 2014-12-04
KR20160012223A (ko) 2016-02-02
EP3005383B1 (de) 2019-10-09
CN105229759B (zh) 2017-06-30
CN105229759A (zh) 2016-01-06

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